A case study interested in the way that carbon credits are constructed as fact or as fiction, how they are objects of dispute due to difficulties of establishing credible and verifiable emission savings, but also due to their cultural meaning being formed through carbon footprint calculators and apps that register carbon data. The institutionalisation of carbon as a financial asset regulates emissions-heavy industries, but it has also contributed to the semiotic revaluation of carbon as a cultural and moral artefact.